1. Material selection
Geo-synthesis/ Geo-textile shall meet the material requirements of the specification. The Geo-synthesis shall be covered within the storage to minimize potential damage before installation. The geo-textile which are uncovered should not remain for longer than 7 days after installation. U.V stabilized materials shall not remain exposed to the atmosphere longer than 14 days after installation.
Excavate the trench, place the geo-textile along the perimeter and add bedding for drainage. Place the drainage aggregate and compact, wrap the geo-textile over the top of the drainage and backfill and compact the top.
The process of installation in detail are explained below:
A. Excavation and preparing the trench
Excavate the trench using chain trencher or other trenching method approved by the engineer. Ensure that trench is wide enough so that backfill may be properly placed and compacted. Prepare the bottom and side of the trench so that no damage will occur to the geo-textile upon placement. To minimize damage, the bottom and side of the trench shall be smooth and free of stone, grids and other irregularities that might puncture or damage the geo-textile. Construction equipment should never be operated directly on the geo-textile.
B. Geo-textile placement
The graded surface of the bottom of trenches shall be smooth and free from debris. When placing the geo-textile, it shall be unrolled in the line with the placement of new aggregate. The geo-textile shall be placed free of tension, stress or wrinkles and with minimal voids between geo-textile and ground surface. Place a sufficient width of geo-textile to entirely cover the perimeter of the trench allows for the required overlap. Successive sheets of geo-textile can be overlapped a minimum of 12 inches with the upstream sheet overlapping the downstream sheet.
C. Damage repair
If the geo-textile is damage during installation or damage aggregate placement, a geo-textile patch shall be placed over the damaged area extending beyond the damaged area at a distance of 3 ft.
D. Aggregate backfill
Placement of drainage aggregate should proceed immediately following the placement of geo-textile. The geo-textile should be covered with a minimum of 12” of loosely placed aggregate with proper compaction.
In trenches equal to or greater than 12” wide after placing the drainage shall be folded over the top of the backfill material. In a manner to produce a minimum of 12” overlap. In trenches lesser than 12” and greater than 4” wide, the overlap shall be equal to the width of the trench. When the trench is lesser than 4” wide, the geo-textile shall be sewed or bonded.
The aggregate or backfilling should be compacted with vibrating equipment to the density required. If high compaction effort is required a higher survivability geo-textile should be considered.